Composition useful in making extensible films

ABSTRACT

Cured coatings having a high degree of extensibility, gloss retention, good sprayability and other desirable properties are obtained from compositions comprising (A) an interpolymer of a hydroxyalkyl ester of an ethylenically-unsaturated carboxylic acid and a copolymerizable material; (B) an organic polyisocyanate; (C) a polymeric polyol of low gloss transition temperature; and (D) a curing agent, present either externally and/or as a part of the interpolymer. These compositions, when used as coatings, are durable, adherent and highly extensible. The coatings are particularly useful on resilient and rubbery substrates such as EPDM rubber, foam rubber, polyurethane foam and vinyl foam and on soft metal surfaces such as steel and aluminum.

United States Patent Chang et al.

COMPOSITION USEFUL IN MAKING EXTENSIBLE FILMS [75] Inventors: Wen-HsuanChang; J. Alden Erikson, both of Gibsonia; Samuel Porter, .lr.,Tarentum, all of Pa.

[73] Assignee: PPG Industries, Inc., Pittsburgh, Pa.

[22] Filed: Aug. 29, 1973 [2|] Appl. No.2 392,585

[52] US. Cl 260/850; 260/75 NP; 260/775 CR; 260/841; 260/844; 260/851;260/856; 427/42]; 427/430; 427/435; 428/425 [51] Int. Cl. C08L 61/20;C081. 67/00 [58] Field of Search... 260/850, 85], 856, 77.5 CR, 260/75NP [56] References Cited UNITED STATES PATENTS 3.218.280 ll/l965 Koral260/90l 3.384.606 5/l968 Dieterich et al 260/850 3.557.043 l/l97l Krausset al. 260/85] Primary Examiner-Murray Tillman Assistant Eraminer-JZiegler Attorney, Agent. or Firm-William .l. Uhl

[ ABSTRACT Cured coatings having a high degree of extensibility, glossretention, good sprayability and other desirable properties are obtainedfrom compositions comprising (A) an interpolymer of a hydroxyalkyl esterof an ethylenically-unsaturated carboxylic acid and a copolymerizablematerial; (B) an organic polyisocyanate; (C) a polymeric polyol of lowgloss transition temperature; and (D) a curing agent, present eitherexternally and/or as a part of the 'interpolyrner. These compositions,when used as coatings, are durable. adherent and highly extensible. Thecoatings are particularly useful on resilient and rubbery substratessuch as EPDM rubber, foam rubber, polyurethane foam and vinyl foam andon soft metal surfaces such as steel and aluminum 13 Claims, No DrawingsCOMPOSITION USEFUL IN MAKING EXTENSIBLE FILMS I BACKGROUND OF THEINVENTION Recent advances in coating technology have provided coatingswhich are suitable for use over various substrates which are difficultto coat and which have many different properties. Coatings of excellentappearance, a high order of durability and having the ability towithstand severe environmental conditions have been obtained. Among themore advanced coatings are those employed on vehicles, such asautomobiles, where good appearance must be maintained over long periodsdespite exposure to weather and various forms of attack during use.

Recently, there has been interest in the use of rubbery, resilientmaterials for areas which are subject to mechanical shock, such asautomobile bumpers and moldings, exposed corners and surfaces ofindustrial machines, kickplates and other areas of doors and entrances,and the like. The use of such materials aids in providing protectionagainst permanent structural damage. In order to attain the describedappearance, a decorative and protective coating must be applied to thesurface and this coating can also be damaged during use. Conventionalcoatings, including those employed on rubber and similar extensibleobjects heretofore, do not have the required combination of properties.These necessary properties include:

1. Extensibility This property is necessary in order that the advantagesof the resilient substrates can be utilized without destruction of theintegrity of the surface of the coating.

2. Tensile Strength A high degree of tensile strength is also necessaryin order to avoid rupture of the film during use.

3. Package Stability In order to permit ease of application, the liquidcoating composition should be stable for extended periods under ambientconditions without either gelation or depolymerization of the resincontained therein.

4. Film Stability Certain coatings which are extensi' ble and which havea relatively high tensile strength lose those properties upon aging andparticularly if the coating is exposed to sunlight, weathering, etc.

5. Impact Resistance The coating should have adequate impact resistanceat various temperatures as encountered in extreme weather variations,including temperatures as low as F. and as high as 120F.

6. Adhesion The coating should have satisfactory adhesion to the varioussubstrates with which it is to be employed, including extensiblematerials such as foams, rubber and the like, and metals such as mildsteel. In addition, the coatings should have satisfactory intercoatadhesion with suceeding coats or with various primers which can beemployed.

7. Chemical and Humidity Resistance This includes properties such assaponification resistance upon exposure to acids and alkalis, resistanceto various solvents and resistance to atmospheres of high humidity andheat.

8. Resistance to Cracking Under Temperature-Humidity Cycling Thisproperty is important where the coating might be exposed to rapidvariations in temperature and humidity as might be encountered byautomobiles during travel or storage. This property is 2 tested bysuccessively exposing the coated object to conditions of hightemperature and high humidity alternated with exposure to lowtemperature and tow humidity.

to atomize. lf the solvent concentration is below the minimum, thepolymer will form a stringy, web spray pattern. The sprayability of aresin will generally be a close indication of the sprayability of thepaint or coating formulation.

It is especially difficult to obtain the above properties in combinationsince, in most instances, the obtaining of one or several of theproperties desired requires the use of materials and formulations whichunder ordinary circumstances tend to make the other desired propertiesless satisfactory.

SUMMARY OF THE INVENTION The one-package stable compositions of thepresent invention comprise the ungelled reaction product of an organicpolyisocyanate. a polymeric polyol of low glass transition temperature,an interpolymer of a hydroxyalkyl ester of an ethylenically unsaturatedcarboxylic acid and at least one other copolymerizable ethylenicallyunsaturated compound, and a curing agent. The curing agent may beexternal, i.e., added to the other three components, and will generallybe selected from the group consisting of aminoplast resins, phenolicresins, blocked polyisocyanates and masked polyisocyanates.Alternatively, the curing agent may be internal as byinterpolymerization with the hydroxyalkyl ester, and can be either analkoxymethyl-containing acrylamide or a blocked or maskedpolyisocyanate.

Such coatings can be applied to virtually any solid substrate and areespecially useful on rubbery, resilient substrates such as polyurethaneor polyurethane foam, natural or synthetic rubber foam, and variouselastomeric materials. They are also useful on other substrates such asmild steel or aluminum.

The coatings herein provide all the above-mentioned properties to asatisfactory degree and have a combination of these properties notheretofore considered possible.

DETAILED DESCRIPTION OF THE INVENTION The composition of the inventioncomprises the reaction product of an organic polyisocyanate, a polymericpolyol, an interpolymer of a hydroxyalkyl ester and at least one othercopolymerizable ethylenically unsaturated compound, and a curing agentpresent either externally or internally.

The interpolymer of the instant invention is an interpolymer of ahydroxyalkyl ester of an ethylenically unsaturated carboxylic acid andone or more copolymerizable ethylenically unsaturated compounds. Theinterpolymer should have a hydroxyl value of from about 4 to about 200.

The preferredinterpolymers are those containing hydroxy groups derivedfrom monoacrylates or methacrylates of a diol such as hydroxyalkylacrylates and methacrylates. Examples include acrylic acid andmethacrylic acid esters of ethylene glycol and 1,2-propylene glycol suchas hydroxyethyl acrylate and methacrylate and hydroxypropyl methacrylateas well as polyethylene glycol monoacrylate and polycaprolactone diol orpolyol monoacrylate. Hydroxybutyl acrylate, hydroxyoctyl methacrylate,and the like are further examples of the hydroxyalkyl esters of theinterpolymer. Also useful are the hydroxy-containing esters of suchunsaturated acids as maleic acid, fumaric acid, itaconic acid, and thelike. The hydroxyalkyl ester generally has a molecular weight in therange of from about 100 to about I500 and preferably from about l toabout 1000.

The monomer or monomers with which the hydroxyalkyl ester isinterpolymerized can be any ethylenically unsaturated compoundcopolymerizable with the ester, the polymerization taking place throughthe ethylenically unsaturated linkages. These include monoolefinic anddiolefinic hydrocarbons. halogenated monoolefinic and diolefinichydrocarbons, unsaturated esters of organic and inorganic acids, amidesand esters of unsaturated acids, nitriles of unsaturated acids, and thelike. Examples of such monomers includestyrene, butadiene-1,3, methylmethacrylate, acrylamide, acrylonitrile, 2-chlorobutene, alphamethylstyrene, alphachlorostyrene, 2-chloro-l,3-butadiene,l,l-dichloroethylene, vinyl butyrate, vinyl acetate, allyl chloride,dimethyl maleate, divinyl benzene, diallyl itaconate, triallylcyanurate, blends thereof, and the like.

It is noted that the monomer used to form the interpolymer may containtherein (1 an alkoxymethyl-containing acrylamide such as N-alkoxymethylacrylamides, N-alkoxymethylmethacrylamides,alkoxymethyldiacetoneacrylamides, N-( alkoxymethyl)-0- (acryloxyethyl)carbamates, N-methyl-N-alkoxymethylacrylamides, and the like; (2)ethylenically unsaturated blocked isocyanates such as the reactionproduct of isophorone diisocyanate, hydroxyethyl acrylate, and butanolor s-caprolactam; or (3) ethylenically unsaturated masked isocyanatessuch as N-(trimethylamino)- methacrylamide. These materials are theninterpolymerized with the hydroxyalkyl ester to form compositions whichmay be cured without the necessity of the addition of external curingagent. if desired, however, an aminoplast resin, a phenolic resin, amasked or a blocked polyisocyanate curing agent may be added to thecomposition.

While the amounts of hydroxyalltyl ester, copolymerizable monomer and,if desired, internal curing agent, may be varied over a wide range, itis preferable that the hydroxyalkyl ester comprise from about I to about25 percent by weight of the interpolymer, that the additional monomer ormonomers comprise from about 50 to about 99 percent by weight of theinterpolymer, and that the internal curing agent comprise from 0 toabout 25 percent by weight of the interpolymer.

One particularly preferred interpolymer comprises 4 percent hydroxyethylmethacrylate, 72 percent ethyl acrylate, percent methacrylonitrile and 4percent N-butoxymethylacrylamide.

The polyisocyanate which is reacted with the polymeric polyol and theinterpolymer can be essentially any organic polyisocyanate, e.g.,hydrocarbon polyisocyanates or substituted hydrocarbon diisocyanates.

4 Many such organic polyisocyanates are known in the art, includingp-phenylene diisocyanate, biphenyl diisocyanate, toluene diisocyanate,3,3'-dimethyl-4,4'- biphenylene diisocyanate, l,4-tetramethylenediisocyanate, hexamethylene diisocyanate,2,2,4-trimethylhexane-l,6-diisocyanate, methylene-bis(phenylisocyanate), lysine methyl ester diisocyanate,bis(isocyanatoethyl)fumarate, isophorone diisocyanate and methylcyclohexyl diisocyanate. There can also be employedisocyanate-terminated adducts of diols, such as ethylene glycol,l,4-butylene glycol, polyalkylene glycols, and the like. These areformed by reacting more than one equivalent of a diisocyanate, such asthose mentioned, with one equivalent of a diol to form a longer chaindiisocyanate. Alternatively, the diol can be added along with thediisocyanate.

While diisocyanates are preferred, higher polyisocyanates can beutilized as part of the organic polyisocyanate. Examples are1,2,4-benzene triisocyanate and polymethylene polyphenyl isocyanate.

It is preferred to employ an aliphatic diisocyanate, since it has beenfound that these provide better color stability in the finished coating.Examples include bis- (isocyanatocyclohexyl)methane, l,4-butylenediisocyanate, isophorone diisocyanate and methylcyclohexylenediisocyanate.

The polymeric polyol to be reacted has a glass transition temperaturebelow about 50C. The method of measuring the glass transitiontemperature of a polymeric polyol will depend upon the molecular weightand other physical properties. If the molecular weight is high, the Tgis usually measured with a penatrometer (Instruction Manual, DuPont 900Differential Thermal Analyzer Accessories", I968, Section 1 1-8). For

low molecular weight cyrstalline polyols, the wellknown relationship,Tm/T g 3/2 (Tm melting point), can be used. For non-crystalline polyols,if the Tg is below about 50C., the polyol will flow below thattemperature. Many Tg values for various polyols are available in theliterature. Also helpful in determining the Tg is the well knownClash-Berg method, described in ADVANCES IN POLYURETHANE TECHNOL- OGY,Burst et al., Wiley 8: Sons, 1968, pages 84 ff.

Among the preferred polymeric polyols are polyether polyols; especiallypreferred are poly(oxyalkylene)- glycols such as poly( oxyethyleneglycol), poly(oxypropylene glycol) and other such glycols having up to 6carbon atoms separating each pair of oxygen atoms. A specific preferredpolyol is poly(oxytetramethylene)- glycol.

Other highly desirable polymeric polyols are polyester polyols havingthe desired transition temperature, especially those produced fromacyclic reactants such as adipic acid and azelaic acid and alkyleneglycols; poly( neopentyl adipate) is a useful example. It is desirablein some cases to include small amounts of cyclic compounds in theformation of the polyester polyols of this invention, and for thispurpose, up to about 20 percent by weight of cyclic acids and/oralcohols may be used, provided that the Tg of the polyol is kept belowabout 50C. Still other polymeric polyols of suitable properties includecondensates of lactones and polyalcohols, such as those produced fromcaprolactone and ethylene glycol, propylene glycol, trimethylolpropane,and the like. In general, the polyols used should have molecular weightsbetween about 200 and about 5,000, and preferably from about 250 toabout 1500.

Also useful are soft polymeric acrylic polyols having glass transitiontemperatures less than 50C., such as interpolymers of hydroxyalkylacrylates and methacrylates and large amounts of other copolymerizablematerials, such as lauryl metacrylate, 2-ethylhexyl acrylate, n-butylacrylate, and the like. If a soft acrylic polyol is used, the polyolmust have a glass transition temperature at least degrees C lower thanthat of the interpolymer described above which is reacted with theisocyanate and the polymeric polyol.

Polyurethane polyols such as, for example, those prepared by reactingany of the above polyols with a minor amount of polyisocyanate (OH/NCOratio greater than 1:l) so that free hydroxyl groups are present in theproduct, may also be used herein.

It is also noted that low molecular weight polyols having molecularweights of less than 200, such as ethylene glycol, ester-containingdiols, and the like, may also be added as part or all of the polymericpolyol component. The use of the term polymeric polyol" is meant toinclude such materials.

if the interpolymer described above does not contain a curing agentinternally, as described above, a curing agent selected from the groupconsisting of aminoplast resins, phenolic resins, blockedpolyisocyanates and masked polyisocyanates, is added in order to form acurable coating composition which can be sprayed and which hasacceptable film properties. If the interpolymer does contain curingagent internally, the above curing agent is not necessary, althoughsatisfactory results are attainable if an external curing agent is alsoused.

The aminoplast resins used may be alkylated methylol melamine resins,alkylated methylol urea, and similar compounds. Products obtained fromthe reaction of alcohols and formaldehyde with melamine, urea orbenzoguanamine are most common and are preferred herein. However,condensation products of other amines and amides can also be employed,for example, aldehyde condensates of triazines, diazines, triazoles,guanadines, guanamines and alkyland aryl-substituted derivatives of suchcompounds, including alkyland aryl-substituted ureas and alkylandaryl-substituted melamines. Some examples of such compounds areN,N'-dimethyl urea, benzourea, dicyandimide, formaguanamine,acetoguanamine, ammeline, 2-chloro- 4,6-diamino-l ,3,5-triazine,6-methyl-2,4-diamino- 1,3,5-triazine, 3,5-diaminotriazole,triaminopyrimidine, 2-mercapto-4,6-diaminopyrimidine,3,4,6-tris(ethylamino)-l,3,S-triazine, and the like.

While the aldehyde employed is most often formaldehyde, other similarcondensation products can be made from other aldehydes, such asacetaldehyde, crotonaldehyde, acrolein, benzaldehyde, furfural, glycoland the like.

The aminoplast resins contain methylol or similar alkylol groups, and inmost instances at least a portion of these alkylol groups are etherifiedby a reaction with an alcohol to provide organic solventsoluble resins.Any monohydric alcohol can be employed for this purpose, including suchalcohols as methanol, ethanol, propanol, butanol, pentanol, hexanol,heptanol and others, as well as benzyl alcohol and other aromaticalcohols, cyclic alcohol such as cyclohexanol, monoethers of glycolssuch as Cellosolves and Carbitols, and halogensubstituted or othersubstituted alcohols, such as 3- 'chloropropanol and butoxyethanol. Thepreferred aminoplast resins are substantially etherified with methanolor butanol.

The phenolic resins which may be used as curing agents herein are formedby the condensation of an aldehyde and a phenol. The most used aldehydeis formaldehyde, although other aldehydes, such as acetaldehyde, canalso be employed. Methylene-releasing and aldehyde-releasing agents,such as paraformaldehyde and hexamethylene tetramine, can be utilized asthe aldehyde agent if desired. Various phenols can be used; forinstance, the phenol employed can be phenol per se, a cresol, or asubstituted phenol in which a hydrocarbon radical having either astraight chain, a branched chain or a cyclic structure is substitutedfor a hydrogen in the aromatic ring. Mixtures of phenols are also oftenemployed. Some specific examples of phenols utilized to produce theseresins include p-phenylphenol, ptert-butylphenol, p-tert-amylphenol,cyclopentylphenol and unsaturated hydrocarbon-substituted phenols, suchas the monobutenyl phenols containing a butenyl group in ortho, meta orpara position, and where the double bond occurs in various positions inthe hydrocarbon chain. A common phenolic resin is phenol formaldehyde.

Any blocked organic polyisocyanate may be used as the curing agentherein. The conventional organic polyisocyanates, as described above,which are blocked with a volatile alcohol, c-caprolactam, ketoximes orthe like, so that they will be unblocked at temperatures above C. may beused. These curing agents are well known in the art.

A masked polyisocyanate may also be used as the curing agent. Thesemasked polyisocyanates, as is known in the art, are not derived fromisocyanates, but do produce isocyanate groups upon heating at elevatedtemperatures. Examples of useful masked polyisocyanates includediaminimides adiponitrile dicarbonate, and the like.

The curing agent may comprise up to about 60 percent by weight of thecoating composition and prefe rably comprises from about 4 to about 50percent by weight of the coating composition.

The reaction product of the invention may be obtained by any of a numberof processes. For example, where the interpolymer does not contain aninternal curing agent, the isocyanate and polymeric polyol may bepre-reacted to form an isocyanate-terminated prepolymer. Subsequently,the prepolymer may be reacted with the interpolymer, either in thepresence of the curing agent or before the addition of the curing agent.Alternatively, the isocyanate, polymeric polyol and interpolymer may besimultaneously reacted together, either in the presence of the curingagent, or prior to addition of the curing agent.

Where the interpolymer internally contains a curing agent, theisocyanate and polymeric polyol may be prereacted to form anisocyanate-terminated prepolymer, and subsequently reacted with theinterpolymer. Alternatively, the isocyanate, polymeric polyol andinterpolymer may be reacted together simultaneously. in the instanceswhere both external and internal curing agents are used, the sequence ofreaction steps may be varied in a similar manner.

Regardless of the method chosen, the sequence of reactive steps isgenerally selected so that gellation can be avoided. Further, all thereactions may be conducted at room temperature or higher, and in thepresence or absence of catalysts such as tin catalysts, tertiary aminesand the like.

in order to produce a solvent soluble product, it is important that theequivalent ratio of isocyanate groups to hydroxyl groups at the variousreaction stages be carefully controlled. When the isocyanate andpolymeric polyol are prereacted to form the isocyanate-terminatedprepolymers, the proportion of each may be widely varied; however, inorder to prevent gellation when the prepolymer is subsequently reactedwith the interpolymer, and in order to insure the production of anisocyanate-terminated prepolymer, the equivalent ratio of isocyanategroups to hydroxyl groups should be between about l.l:l to about 3:1.Some monofunctional amine or alcohol may be added to reduce thefunctionality of the prepolymer. When the isocyanate, polymeric polyoland interpolymer are reacted simultaneously (in the presence or absenceof curing agents) and when the prepolymers are reacted with theinterpolymers (in the presence or absence of curing agents), theequivalent ratio of isocyanate groups to hydroxyl groups should bebetween about [11.1 and about 1:9. Again, monofunctional amines oralcohols as well as hydroxy amines may be added to prevent gellation. Itis noted that water (e.g., in the form of moisture in the air) willcontribute hydroxy groups to the reaction mixture. In fact, in someinstances, it may be desirable to add small amounts of water to thereaction mixture.

The amount of each component in the composition may be varied over awide range. in general, however, the polyisocyanate comprises from abouti to about 30 percent by weight of the composition, the polymeric polyolcomprises from about 2 to about 60 percent by weight of the composition,the external curing agent comprises from to about 50 percent by weightof the composition, the internal curing agent comprises from 0 to about25 percent by weight of the interpolymer and the interpolymer comprisesfrom about 30 to about 95 percent by weight of the composition. Thetotal amount of curing agent in the composition should be at one andpreferably at least 3 percent by weight.

In addition to the components above, the compositions ordinarily containother optional ingredients, including any of the various pigmentsordinarily utilized in coatings of this general class. In addition,various fillers, plasticizers, antioxidants, flow control agents,surfactants, and other such formulating additives can be employed inmany instances. The composition is ordinarily contained in a solvent,which can be any solvent or solvent mixture in which the materialsemployed are compatible and soluble to the desired extent.

The compositions herein can be applied by any con ventional method,including brushing, dipping, flow coating, and the like, but they aremost often applied by spraying. Usual spray techniques and equipment areutilized. They can be applied over virtually any substrate, includingwood, metals, glass, cloth, plastics, foams, and the like, as well asover various primers.

The coatings are cured at room temperature or elevated temperatures. inmost cases the cure schedule is from about one minute to several days at75F. to 400F. Higher or lower temperatures with correspondingly shorterand longer times can be utilized, although the exact cure schedule bestemployed depends in part upon the nature of the substrate as well as theparticular components of the composition. Acid catalysts and othercuring catalysts such as dibutyltin dilaurate can be added to aid incuring if desired; these permit the use of lower temperatures and/orshorter times. if suffcient amount of catalyst is added, curing at roomtemperatures is often possible.

While only a one-package system has been specifically disclosed, it isto be understood that good results are also attained by using atwo-package system, i.e., through the use of an unblocked or unmaskedpolyisocyanate curing agent.

The invention will be further described in connection with severalexamples which follow. These examples are given as illustrative of theinvention and are not to be construed as limiting it to their details.All parts and percentages in the examples and throughout thespecification are by weight unless otherwise indicated.

EXAMPLE 1 A reactor was charged with 440 parts of his-(isocyanatocyclohexyl) methane (Hylene W, E. l. Du- Pont Chemical Co.),1440 parts of a polycaprolactone diol (having a molecular weight of1250), 500 parts of methylbutyl ketone and 0.02 part of dibutyltindilaurate. The reactants were heated at 100C. for 2 hours in a nitrogenatmosphere.

To a reactor were charged 560 parts of the above prepared prepolymer,600 parts of an interpolymer [comprising 49 percent solids in a blend ofmethyl butyl ketone (65%) and high boiling point naphtha solvent (35%)of 42 percent methyl methacrylate, l3 percent methacrylonitrile, 27percent lauryl methacrylate, 9 percent hydroxyethyl acrylate and 9percent butyl methacrylate, the interpolymer had a Gardner-Holdtviscosity of X-Y and a hydroxyl value of about 22], 7.5 parts ofisopropanolamine, 340 parts of methyl butyl ketone and one drop ofdibutyltin dilaurate catalyst. The reactants were heated at C. in anitrogen atmosphere for l0 hours. Gellation was prevented at this pointby addition of 3.9 parts of monoethanolamine.

The resulting composition was cured with melamine formaldehyde resin(Cymel 303, American Cyanamid) in an amount equal to about 20 percent byweight at 300F. for 30 minutes. The film had excellent tensile strength,elongation, flexibility and exterior gloss retention.

EXAMPLE ll A reactor was charged with 2300 parts ofpolyoxytetramethylene glycol having a molecular weight of l000 (Polymeg1000), 880 parts of l-lylene W, 820 parts of methyl butyl ketone, and0.03 part of dibutyltin dilaurate, the reactants were heated for 3 hoursat C.

A reactor was then charged with 254 parts of the above preparedprepolymer, 600 parts of the interpolymer of Example I, 146 parts ofmethyl butyl ketone, 4.0 parts of isopropanolamine and 1 drop ofdibutyltin dilaurate. The reactants were heated in a nitrogen atmosphereat 100C. for 35: hours at which point 2.6 parts of monoethanolamine wereadded to prevent gellation.

The resulting resin was blended with butylated melamine formaldehyderesin (in an amount equal to about 25 percent by weight) in the presenceof 0.25 percent p-toluene sulfonic acid catalyst and coated onto a foamsubstrate and baked at 250F. for 30 minutes to form an extensible,impact resistant and flexible coating.

EXAM PLE III A reactor was charged with 60 parts of the acrylicinterpolymer of Example 1, 50 parts of a polyurethane polyol [which isthe reaction product of 1250 parts of polycaprolactone diol (molecularweight 1250 and 195 parts of Hylene W 3 parts of l-lylene W, 20 parts ofmethyl butyl ketone and 18.5 parts of melamine formaldehyde resin (Cymel303, American Cyanamide The reactants were heated at 75C. for 4 hours.

To parts of the above composition was added 0.02 part of p-toluenesulfonic acid and the mixture was drawn down on a clean steel panel andbaked at 300F. for 30 minutes. The resulting film was clear, hard andhad good adhesion. The impact resistance and solvent resistance wereexcellent.

EXAMPLE IV An isocyanate terminated prepolymer was made by charging to areactor 1760 parts of Hyle ne W, 5760 parts of polycaprolactone diol(molecular weight 1250), 2000 parts of methyl butyl ketone and 0.08 partof dibutyltin dilaurate. The reactants were heated at 100C. for 2 hours.

To 580 parts of the above isocyanate prepolymer were added 600 parts ofan interpolymer containing an internal curing agent {comprising 47.5percent solids in a solvent blend of methyl butyl ketone and highboiling naphtha (65/35) of 625 parts of methyl methacrylate, 200 partsof acrylonitrile, 400 parts of lauryl methacrylate, 148 parts ofhydroxyethyl acrylate, 130 parts of butyl methacrylate and 148 parts ofN-isobutoxymethylacrylamide, with a Gardner-Holdt viscosity of 2 -2,,and an OH value of about 27], 320 parts of methyl butyl ketone, 8.1parts of isopropanolamine and 1 drop of dibutyltin dilaurate and thereactants were heated for two hours at 100C. A film of the resultingresin was cured in the presence of 0.2 percent of p-toluene sulfonicacid catalyst at 325F. for 30 minutes to yield a film having excellentimpact resistance.

EXAMPLE V To parts of the resin of Example IV were added 2 parts ofmelamine-formaldehyde resin (Cymel 303), 0.02 part of p-toluene sulfonicacid catalyst and 3.0 parts of a 3/1 solvent mixture of isopropylalcohol and butyl alcohol.

The mixture was drawn down on a clean steel panel and baked at 325F. forminutes. The resultant film had excellent impact resistance andflexibility.

EXAMPLE VI A reactor was charged with 60 parts of the interpolymer ofExample 1, 50 parts of the polyurethane polyol of Example III, 1.5 partsof Hylene W, 20 parts of methyl butyl ketone, 1 part of n-butanol and 2drops of dibutyltin dilaurate. The reactants were heated at 150C. for 4hours until no NCO remained.

To 10 parts of the above composition were added 2.1 parts of Cymel 303and 0.02 part of p-toluene sulfonic acid and the composition was coatedonto a steel substrate and baked at 250F. for 30 minutes. The resultingfilm had good flexibility, excellent impact resistance and good marresistance.

EXAMPLE v11 An isocyanate prepolymer was made from 250 parts of apoly(oxytetramethylene)glycol of a molecular weight of 1000 (Polymeg1000) and 92 parts of methylcyclohexylene diisocyanate. The reactantswere heated at 150C for 16 hours.

To 59.1 parts of the above pre-reacted product were added 700 parts ofan interpolymer containing an internal curing agent (comprising 60.4percent solids in xylene of 4 percent n-butoxymethylacrylamide, 4percent hydroxyethyl methacrylate, 20 percent methacrylonitrile and 72percent ethyl acrylate; the interpolymer had a Gardner-Holdt viscosityof Z 29 parts of methyl butyl ketone and 1 part of tin octanoate. Thereactants were heated at 118C. for 11% hours.

To the above composition was added 0.02 parts of p-toluene sulfonicacid. The composition was applied to a steel substrate and was cured at325F. for 30 minutes to form an excellent extensible coating.

EXAMPLE VI" A reactor was charged with 13 parts of l-lylene W, 500 partsof a soft acrylic polyol having a low glass transition temperature(comprising 44.8 percent solids of 65 percent butyl methacrylate, 30percent methyl methacrylate and 5 percent hydroxyethyl acrylate; theinterpolymer had a Gardner-Holdt viscosity of E-F and an 01-1 value ofabout 12), and 500 parts of the interpolymer of Example 1. After theaddition of one drop of p-toluene sulfonic acid, the reactants wereheated at C. for 4 hours.

To the above composition was added Cymel 303 in an amount equal to about20 percent by weight. The composition was applied to a steel substrateand cured at 300F. for 30 minutes to yield a film having excellentflexibility.

According to the provisions of the patent statutes, there are describedabove the invention and what are now considered to be its bestembodiments. However, within the scope of the appended claims, it is tobe understood that the invention can be practiced otherwise than asspecifically described.

We claim: 1. A coating composition consisting essentially of: A. anungelled reaction product of:

1. 1-30 percent by weight of an organic polyisocyanate; 2. 2-60 percentby weight of a polymeric polyol having a glass transition temperature ofless than 50C.; 3. 30-95 percent by weight of an interpolymer of:

a. a hydroxyalkyl ester of an ethylenically unsaturated carboxylic acid;and

b. at least one other copolymerizable ethylenically unsaturated monomer;

said interpolymer being different from said polymeric polyol; when saidpolymeric polyol is a polymeric acrylic polyol, the polymeric acrylicpolyol having a glass transition temperature at least 10C. lower thanthat of the interpolymer;

the equivalent ratio of isocyanate groups to hydroxyl groups in (1), (2)and (3) being between 1:1.1 and about 1:9; and

B. at least [-60 percent by weight of an amine-aldehyde condensatecuring agent.

2. The composition of claim 1, wherein said hydroxy alkyl ester isselected from the group consisting of hydroxyalkyl acrylates andmethacrylates.

3. The composition of claim 2, wherein said polymeric polyol is apolyether polyol.

4. The composition of claim 3, wherein said polyether polyol is apoly(oxyalkylene)glycol.

5. The composition of claim 1 additionally containing a low molecularweight polyol having a molecular weight of less than 200.

6. The composition of claim 1, wherein said polymeric polyol is apolyester polyol.

7. The composition of claim 1, wherein said polymeric polyol is selectedfrom the group consisting of polyester polyols and polyether polyols.

8. The composition of claim I, wherein said polymeric polyol is apolycaprolactone diol, wherein said interpolymer is the interpolymer ofmethyl methacrylate, methacrylonitrile, lauryl methacrylate, butylmethacrylate and hydroxyethyl acrylate, and wherein said curing agent isa melamine formaldehyde resin.

9. A method of producing an ungelled extensible composition whichcomprises:

i. reacting at room temperature or higher:

A. 1-30 percent by weight of an organic polyisocy- 1 2. at least oneother iopolymerizable ethylenically unsaturated monomerysaidinterpolymer being different from said polymeric polyol; when thepolymeric polyol is an acrylic polyol, the polymeric acrylic polyolhaving a glass transition temperature at least l0 degrees C. lower thanthat of the interpolymer to form a reaction product in which theequivalent ratio of isocyanate groups to hydroxyl groups in (A), (B) and(C) above is between l:l.l and about 1:9; and

2. curing said reaction product at a temperature of -400F. for oneminute to several days with at least one percent by weight of anamine-aldehyde condensate curing agent.

10. The method of claim 9, wherein the isocyanate and the polymericpolyol are prereacted and subsequently reacted with the interpolymer andcuring agent, and wherein the equivalent ratio of isocyanate to hydroxylin the prereaction mixture is from 1.121 to 3:l.

11. The method of claim 10, wherein the equivalent ratio of isocyanateto hydroxyl in the reaction mixture is from about [21.1 to about 1:9.

[2. The method of claim 9, wherein said polymeric polyol is selectedfrom the group consisting of polyester polyols and polyether polyols.

13. The method of claim 9, wherein said polymeric polyol is apolycaprolactone diol, wherein said interpolymer is the interpolymer ofmethyl methacrylate, methacrylonitrile, lauryl methacrylate, butylmethacrylate and hydroxyethyl acrylate, and wherein said curing agent isa melamine formaldehyde resin.

l t i

1. A COATING COMPOSITION CONSISTING ESSENTIALLY OF: A. AN UNGELLEDREACTION PRODUCT OF:
 1. 1-30 PERCENT BY WIGHT OF ORGANIC POLYISOCYANATE,2. 2-60 PERCENT BY WEIGHT OF A POLYMERIC POLYOL HAVING A GLASS TRANITIONTEMPERATURE OF LESS THAN 50*C,
 3. 30-95 BY WEIHT OF AN INTERPOLYMER OF:A. A HYDROXYALKYL ESTER OF AN ETHYLENICALLY UNSATURATED CARBOXYLIC ACID,AND B. AT LEAST ONE OTHER COPOLYMERIZABLE ETHYLENICALLY UNSATURATEDMONOMER, SAID INTERPLOYMER BEING DIFFERENT FROM SAID POLYMERIC POLYOL,WHEN SAID POLYMEIC ACRYLIC POLYOL HAVING A ACRYLIC POLYOL, THE POLYMEICACRYLIC POLYOL HAVING A GLASS TRANSITION TEMPERATURE AT LEAST 10*C.LOWER THAN THAT OF THE INTERPOLYMER, THE EQUIVALENT RATIO OF ISOCYANATEGROUPS TO HYDROXYL GROUPS IN (1), (2) AND (3) BEING TAKEN BETWEEN 1:1.1AND ABOUT 1:9, AND B. AT LEAST 1-60 PERCENT BY WEIGHT OF ANAMINE-ALDEHYDE CONDENSATE CURING AGENY.
 2. 2-60 percent by weight of apolymeric polyol having a glass transition temperature of less than50*C.;
 2. The composition of claim 1, wherein said hydroxyalkyl ester isselected from the group consisting of hydroxyalkyl acrylates andmethacrylates.
 2. curing said reaction product at a temperature of75*-400*F. for one minute to several days with at least one percent byweight of an amine-aldehyde condensate curing agent.
 2. at least oneother copolymerizable ethylenically unsaturated monomer; saidinterpolymer being different from said polymeric polyol; when thepolymeric polyol is an acrylic polyol, the polymeric acrylic polyolhaving a glass transition temperature at least 10 degrees C. lower thanthat of the interpolymer to form a reaction product in which theequivalent ratio of isocyanate groups to hydroxyl groups in (A), (B) and(C) above is between 1:1.1 and about 1:9; and
 3. 30-95 percent by weightof an interpolymer of: a. a hydroxyalkyl ester of an ethylenicallyunsaturated carboxylic acid; and b. at least one other copolymerizableethylenically unsaturated monomer; said interpolymer being differentfrom said polymeric polyol; when said polymeric polyol is a polymericacrylic polyol, the polymeric acrylic polyol having a glass transitiontemperature at least 10*C. lower than that of the interpolymer; theequivalent ratio of isocyanate groups to hydroxyl groups in (1), (2) and(3) being between 1:1.1 and about 1:9; and B. at least 1-60 percent byweight of an amine-aldehyde condensate curing agent.
 3. The compositionof claim 2, wherein said polymeric polyol is a polyether polyol.
 4. Thecomposition of claim 3, wherein said polyether polyol is apoly(oxyalkylene)glycol.
 5. The composition of claim 1 additionallycontaining a low molecular weight polyol having a molecular weight ofless than
 200. 6. The composition of claim 1, wherein said polymericpolyol is a polyester polyol.
 7. The composition of claim 1, whereinsaid polymeric polyol is selected from the group consisting of polyesterpolyols and polyether polyols.
 8. The composition of claim 1, whereinsaid polymeric polyol is a polycaprolactone diol, wherein saidinterpolymer is the interpolymer of methyl methacrylate,methacrylonitrile, lauryl methacrylate, butyl methacrylate andhydroxyethyl acrylate, and wherein said curing agent is a melamineformaldehyde resin.
 9. A method of producing an ungelled extensiblecomposition which comprises:
 10. The method of claim 9, wherein theisocyanate and the polymeric polyol are prereacted and subsequentlyreacted with the interpolymer and curing agent, and wherein theequivalent ratio of isocyanate to hydroxyl in the prereaction mixture isfrom 1.1:1 to 3:1.
 11. The method of claim 10, wherein the equivalentratio of isocyanate to hydroxyl in the reaction mixture is from about 1:1.1 to about 1:9.
 12. The method of claim 9, wherein said polymericpolyol is selected from the group consisting of polyester polyols andpolyether polyols.
 13. The method of claim 9, wherein said polymericpolyol is a polycaprolactone diol, wherein said interpolymer is theinterpolymer of methyl methacrylate, methacrylonitrile, laurylmethacrylate, butyl methacrylate and hydroxyethyl acrylate, and whereinsaid curing agent is a melamine formaldehyde resin.